Rotary transformers, and particularly loosely coupled power transformers, are often used for transmitting both data and power between two structures that rotate relative to one another, such as between a vehicle tire and its corresponding wheel axle in a tire pressure sensor system, or for coupling data and power to a steering wheel. As is known in the art, loosely coupled power transformers do not conduct power efficiently between the primary and secondary of the transformer. Instead, a part of the input current into the primary coil stores energy in the leakage inductance of the coil. Prior art structures often include a Zener diode across the primary to absorb the energy of the voltage spike that occurs in the transformer when the current to the primary coil is turned off. More particularly, the Zener diode will conduct current before the drive transistor in the primary side breaks down. However, under this approach, the stored energy is dissipated as heat, thereby wasting the energy built up in the primary coil's leakage inductance and lowering the power coupling efficiency of the transformer.
To overcome this problem, conventional rotary transformer designs tend to focus on methods of increasing the coupling efficiency by constructing a magnetically efficient structure for power transmission, such as by using more expensive, high-efficiency core materials, and then adding a complex load impedance mechanism for providing limited two-way communication through the transformer. This results in an overly complicated structure requiring close mechanical tolerances, which increases the manufacturing cost of the system. Further, the bandwidth for these structures tends to be relatively narrow, which limits the amount of data or the speed at which data can be transmitted between the primary and secondary sides of the transformer.